combining two depth images

[weber_ofir]

I am trying to render 2 different images and save each one of them in an array (colors+depths). then, i want to combine the two images to a final image. For example, look at this code:

int v;
static GLfloat pixelsColor1[1512*1512];
static GLfloat pixelsDepth1[512*512];

static GLfloat pixelsColor2[1512*1512];
static GLfloat pixelsDepth2[512*512];

static GLfloat finalImageColor[1512*1512];

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); //clear all the buffers that are in use.

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glPixelStorei(GL_PACK_ALIGNMENT, 1);


glBegin(GL_POLYGON);
glVertex3f(300.0, -300.0, 200.0);
glVertex3f(300.0, 300.0, 200.0);
glVertex3f(-300.0, 300.0, 200.0);
glVertex3f(-300.0, -300.0, 200.0);
glEnd();

glReadPixels(0, 0, prcView->right, prcView->bottom, GL_RGB, GL_FLOAT, pixelsColor1);
glReadPixels(0, 0, prcView->right, prcView->bottom, GL_DEPTH_COMPONENT, GL_FLOAT, pixelsDepth1);

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); //clear all the buffers that are in use.
//--------------------------------------

glBegin(GL_POLYGON);
glVertex3f(450.0, -300.0, 300.0);
glVertex3f(450.0, 300.0, 300.0);
glVertex3f(-150.0, 300.0, 300.0);
glVertex3f(-150.0, -300.0, 300.0);
glEnd();


glReadPixels(0, 0, prcView->right, prcView->bottom, GL_RGB, GL_FLOAT, pixelsColor2);
glReadPixels(0, 0, prcView->right, prcView->bottom, GL_DEPTH_COMPONENT, GL_FLOAT, pixelsDepth2);

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); //clear all the buffers that are in use.
//--------------------------------------


//////////////// DRAWING /////////////////////////
for(v = 0; v < prcView->right*prcView->bottom; v++){
if(pixelsDepth1[v] <= pixelsDepth2[v]){
finalImageColor[v*3] = pixelsColor1[v*3];
finalImageColor[v*3 + 1] = pixelsColor1[v*3 + 1];
finalImageColor[v*3 + 2] = pixelsColor1[v*3 + 2];
}
else{
finalImageColor[v*3] = pixelsColor2[v*3];
finalImageColor[v*3 + 1] = pixelsColor2[v*3 + 1];
finalImageColor[v*3 + 2] = pixelsColor2[v*3 + 2];
}
}

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); //clear all the buffers that are in use.

glDrawPixels(prcView->right, prcView->bottom, GL_RGB, GL_FLOAT, finalImageColor);

glFinish();
return;

but i am geting a distortions!!
It looks like one of the polygons has a strange frame and it looks shifted.
Is anyone knows what the problem or how it is need to be done?

[weber_ofir]

I wanted to add a remark to my question.
The most annoying and not predicted thing with my problem is that it not always happening. I am running the program and i get the distortion, I am closing it and run it again and get the distortion again(though it a little bit different), then, after a few times i try this, i am geting the right picture. If anyone know what can causing this i will be grateful.